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<b>DbTxn::prepare</b>
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<b><pre>
#include &lt;db_cxx.h&gt;
<p>
int
DbTxn::prepare(u_int8_t gid[DB_XIDDATASIZE]);
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<b>Description: DbTxn::prepare</b>
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<p>The DbTxn::prepare method initiates the beginning of a two-phase commit.</p>
<p>In a distributed transaction environment, Berkeley DB can be used as a local
transaction manager.  In this case, the distributed transaction manager
must send <i>prepare</i> messages to each local manager.  The local
manager must then issue a DbTxn::prepare and await its successful
return before responding to the distributed transaction manager.  Only
after the distributed transaction manager receives successful responses
from all of its <i>prepare</i> messages should it issue any
<i>commit</i> messages.</p>
<p>In the case of nested transactions, preparing the parent causes all
unresolved children of the parent transaction to be committed.  Child
transactions should never be explicitly prepared.  Their fate will be
resolved along with their parent's during global recovery.</p>
<p>The DbTxn::prepare method
either returns a non-zero error value
or throws an exception that encapsulates a non-zero error value on
failure, and returns 0 on success.
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<b>Parameters</b> <br>
 <b>gid</b><ul compact><li>The <b>gid</b> parameter specifies the global transaction ID by which this
transaction will be known.  This global transaction ID will be returned
in calls to <a href="../api_cxx/txn_recover.html">DbEnv::txn_recover</a>, telling the application which global
transactions must be resolved.</ul>
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<br><b>Class</b>
<a href="../api_cxx/env_class.html">DbEnv</a>, <a href="../api_cxx/txn_class.html">DbTxn</a>
<br><b>See Also</b>
<a href="../api_cxx/txn_list.html">Transaction Subsystem and Related Methods</a>
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